face detection iOS from camera

Question

I receive an image view

-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    NSString *mediaType = info[UIImagePickerControllerMediaType];

    [self dismissViewControllerAnimated:YES completion:nil];

    if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
        UIImage *image = info[UIImagePickerControllerOriginalImage];

        //imgvprofileImage.image = image;
        //[self detectForFacesInUIImage:[UIImage imageNamed:@"image00.jpg"]];

        [self detectForFacesInUIImage:image];
    }
    else if ([mediaType isEqualToString:(NSString *)kUTTypeMovie])
    {
        // Code here to support video if enabled
    }
}

When I send a photo like this

[self detectForFacesInUIImage:[UIImage imageNamed:@"image00.jpg"]]; 

The detection works well and finds a face but when I use the image returned from the camera it doesn't work.

 [self detectForFacesInUIImage:image]

This is the function i use to detect the face

-(void)detectForFacesInUIImage:(UIImage *)facePicture
{
    CIImage* image = [CIImage imageWithCGImage:facePicture.CGImage];

    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:[NSDictionary dictionaryWithObject:CIDetectorAccuracyLow forKey:CIDetectorAccuracy]];

    NSArray* features = [detector featuresInImage:image];

    if (features.count == 0) {
        NSLog(@"There is no faces in captured image ") ;
    }

    for(CIFaceFeature* faceObject in features)
    {
        CGRect modifiedFaceBounds = faceObject.bounds;
        modifiedFaceBounds.origin.y = facePicture.size.height-faceObject.bounds.size.height-faceObject.bounds.origin.y;

        [self addSubViewWithFrame:facePicture toRect:modifiedFaceBounds] ;
    }
}

Answer 1

Problem is in image orientation.

Can't remember where I took this, but it works:

- (void) detectForFaces:(CGImageRef)facePicture orientation:(UIImageOrientation)orientation {


    CIImage* image = [CIImage imageWithCGImage:facePicture];

    CIContext *context = [CIContext contextWithOptions:nil];                    // 1
    NSDictionary *opts = @{ CIDetectorAccuracy : CIDetectorAccuracyLow };      // 2
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                              context:context
                                              options:opts];                    // 3

    int exifOrientation;
    switch (orientation) {
        case UIImageOrientationUp:
            exifOrientation = 1;
            break;
        case UIImageOrientationDown:
            exifOrientation = 3;
            break;
        case UIImageOrientationLeft:
            exifOrientation = 8;
            break;
        case UIImageOrientationRight:
            exifOrientation = 6;
            break;
        case UIImageOrientationUpMirrored:
            exifOrientation = 2;
            break;
        case UIImageOrientationDownMirrored:
            exifOrientation = 4;
            break;
        case UIImageOrientationLeftMirrored:
            exifOrientation = 5;
            break;
        case UIImageOrientationRightMirrored:
            exifOrientation = 7;
            break;
        default:
            break;
    }


    opts = @{ CIDetectorImageOrientation :[NSNumber numberWithInt:exifOrientation
                                           ] };

    NSArray *features = [detector featuresInImage:image options:opts];

    if ([features count] > 0) {
        CIFaceFeature *face = [features lastObject];
        NSLog(@"%@", NSStringFromCGRect(face.bounds));
    }
}

How to use:

UIImage *image = // some image here;
[self detectForFaces:image.CGImage orientation:image.imageOrientation];